Converter lock-up question??? (that funny half downshift thing)
Thread Starter
|
Senior Member
Joined: Jun 2002
Posts: 4,293
Likes: 6
Converter lock-up question??? (that funny half downshift thing)
What is torque converter lock up?? Is that when I'm cruising down the highway and my transmission seems like is does kind of a half downshift. The rpm's go up a little, but not as much as turning off overdrive (or doing a full downshift out of overdrive). Did I say that right when I said it locks up??? I live in a windy area so half my driving is in a headwind and it does it constantly. Sometimes it will stay that way for miles...........I know it's for power to avoid a downshift but does it hurt anything to drive like that?
Senior Member
Joined: Nov 2000
Posts: 2,444
Likes: 0
From: DFW, Texas
Sounds like it. It's unlocking when you drop back on the accelerator then it locks back up just after you step back on it. It's normal and you can't change it. And yes, it can be really annoying.
Senior Member
Joined: Mar 2001
Posts: 345
Likes: 0
From: Waterloo, IA
Let me guess...
your trucks motor is a 4.6 liter?
This was probably the #1 reason that I traded my '99 with the 4.6l for a '00 with the 5.4l.
You can feel the TC lock up at about 43 mph, but whenever the computer senses that you need a little more power, it unlocks the TC to avoid lugging the motor (which increases emissions) or to avoid downshifting. This is all designed to create a smooth, environmentaly friendly ride. When you are cruising down the highway, and your truck is confronted with a small hill or stiff wind, the computer unlocks the TC (about a 400 rpm increase on the tach) until the motor doesn't need the extra power, then it locks the TC ( tach goes back to normal cruising rpm). Every time the TC unlocks, it is creating extra heat in the transmission which everyone knows is the #1 killer of transmissions. If your TC is only unlocking a few times per mile, then I wouldn't be concerned. If your TC is like mine was, it would unlock and lock about 20-30 times per mile while cruising at 70+ mph. IMO, this is too much.
When you stomp the gas pedal to the floor to pass someone, your TC unlocks to avoid excessive emissions. That is why your trucks motor makes all kinds of noise, but doesn't seem to really go much faster.
This was probably the #1 reason that I traded my '99 with the 4.6l for a '00 with the 5.4l.
You can feel the TC lock up at about 43 mph, but whenever the computer senses that you need a little more power, it unlocks the TC to avoid lugging the motor (which increases emissions) or to avoid downshifting. This is all designed to create a smooth, environmentaly friendly ride. When you are cruising down the highway, and your truck is confronted with a small hill or stiff wind, the computer unlocks the TC (about a 400 rpm increase on the tach) until the motor doesn't need the extra power, then it locks the TC ( tach goes back to normal cruising rpm). Every time the TC unlocks, it is creating extra heat in the transmission which everyone knows is the #1 killer of transmissions. If your TC is only unlocking a few times per mile, then I wouldn't be concerned. If your TC is like mine was, it would unlock and lock about 20-30 times per mile while cruising at 70+ mph. IMO, this is too much.
When you stomp the gas pedal to the floor to pass someone, your TC unlocks to avoid excessive emissions. That is why your trucks motor makes all kinds of noise, but doesn't seem to really go much faster.
Last edited by OPIE; Jul 5, 2002 at 06:56 PM.
Thread Starter
|
Senior Member
Joined: Jun 2002
Posts: 4,293
Likes: 6
I've got a 5.4L but I have 33" tires with 3.55 limited slip rear. The winds where I live are a killer. Mine doesn't go back and fourth like yours does, or did, but my '97 4.6 did. This one will unlock and stay that way for several miles, or until I start down hill or get out of the wind. Just depends. Not too annoying because it doesn't go back and fourth but still just checking. I am planning on getting a trans temp gauge just for the hell of it to see how it reacts. I am also getting a superchip to see if any extra power will help too.
Senior Member
Joined: Feb 2000
Posts: 1,544
Likes: 0
From: Kalamazoo, MI, USA
I have the same condition as does Galaxy -- but with one twist:
It unlocks -- and stays unlocked for a lonnnnnnnnnng time -- if/when I'm using cruise control and towing a trailer.
Being unlocked, in and of itself, doesn't concern me -- as long as it is INTENDING to stay unlocked.
By that I mean: I hope (don't know if) it is not trying to re-lock but cannot -- that would be deadly (?) for the TC.
Does anyone know if the TC has the clutch capacity to regularly lock up under full 350 lb ft of torque? -- or will it burn itself out by this unlock/lock while towing (Calling Factory Tech!!!)?
It unlocks -- and stays unlocked for a lonnnnnnnnnng time -- if/when I'm using cruise control and towing a trailer.
Being unlocked, in and of itself, doesn't concern me -- as long as it is INTENDING to stay unlocked.
By that I mean: I hope (don't know if) it is not trying to re-lock but cannot -- that would be deadly (?) for the TC.
Does anyone know if the TC has the clutch capacity to regularly lock up under full 350 lb ft of torque? -- or will it burn itself out by this unlock/lock while towing (Calling Factory Tech!!!)?
Member
Joined: Jun 2002
Posts: 84
Likes: 0
Originally posted by FamilyRide
Sounds like it. It's unlocking when you drop back on the accelerator then it locks back up just after you step back on it. It's normal and you can't change it. And yes, it can be really annoying.
Sounds like it. It's unlocking when you drop back on the accelerator then it locks back up just after you step back on it. It's normal and you can't change it. And yes, it can be really annoying.
Well...if you had a chip from someone with a clue..then yes you can change it. TC lockup is controlled via the computer. Mine have been altered on all my EEC-V vehicles so
Seabass
Senior Member
Joined: Mar 2001
Posts: 345
Likes: 0
From: Waterloo, IA
I would be concerned if my trucks TC was staying unlocked for long periods of time, especially while towing. The extra heat is shortening the life of the trans fluid and possibly the life of the transmission itself.
If you notice your TC stalling for long periods of time, you should either turn off the OD or turn off the cruise control and help your truck by anticipating hills with a few extra mph at the bottom, and letting your mph drop slightly while climbing them. Sometimes I set the cruise at a higher mph to get the rpms up into better power/torque band.
The easiest fix for Galaxy's problem would be to buy smaller tires. My last 3 F-150's have all had 31" tires with the 5.4 and 3.55 gears and they didn't have too much trouble with the TC locking or unlocking.
If you notice your TC stalling for long periods of time, you should either turn off the OD or turn off the cruise control and help your truck by anticipating hills with a few extra mph at the bottom, and letting your mph drop slightly while climbing them. Sometimes I set the cruise at a higher mph to get the rpms up into better power/torque band.
The easiest fix for Galaxy's problem would be to buy smaller tires. My last 3 F-150's have all had 31" tires with the 5.4 and 3.55 gears and they didn't have too much trouble with the TC locking or unlocking.